Solid-state NMR spectroscopy to study protein–lipid interactions

The appropriate lipid environment is crucial for the proper function of membrane proteins. There is a tremendous variety of lipid molecules in the membrane and so far it is often unclear which component of the lipid matrix is essential for the function of a respective protein. Lipid molecules and proteins mutually influence each other; parameters such as acyl chain order, membrane thickness, membrane elasticity, permeability, lipid-domain and annulus formation are strongly modulated by proteins. More recent data also indicates that the influence of proteins goes beyond a single annulus of next-neighbor boundary lipids. Therefore, a mesoscopic approach to membrane lipid–protein interactions in terms of elastic membrane deformations has been developed. Solid-state NMR has greatly contributed to the understanding of lipid–protein interactions and the modern view of biological membranes. Methods that detect the influence of proteins on the membrane as well as direct lipid–protein interactions have been developed and are reviewed here. Examples for solid-state NMR studies on the interaction of Ras proteins, the antimicrobial peptide protegrin-1, the G protein-coupled receptor rhodopsin, and the K⁺ channel KcsA are discussed. This article is part of a Special Issue entitled Tools to study lipid functions.